diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -122,7 +122,7 @@
     'rsrc/css/layout/phabricator-source-code-view.css' => '2ceee894',
     'rsrc/css/phui/calendar/phui-calendar-day.css' => '3b4a65d8',
     'rsrc/css/phui/calendar/phui-calendar-list.css' => '840baa8d',
-    'rsrc/css/phui/calendar/phui-calendar-month.css' => '450c37ea',
+    'rsrc/css/phui/calendar/phui-calendar-month.css' => 'b33a35d9',
     'rsrc/css/phui/calendar/phui-calendar.css' => '8345be98',
     'rsrc/css/phui/phui-action-header-view.css' => '89c497e7',
     'rsrc/css/phui/phui-action-list.css' => '4f4d09f2',
@@ -763,7 +763,7 @@
     'phui-calendar-css' => '8345be98',
     'phui-calendar-day-css' => '3b4a65d8',
     'phui-calendar-list-css' => '840baa8d',
-    'phui-calendar-month-css' => '450c37ea',
+    'phui-calendar-month-css' => 'b33a35d9',
     'phui-crumbs-view-css' => '594d719e',
     'phui-document-view-css' => '94d5dcd8',
     'phui-feed-story-css' => 'c9f3a0b5',
diff --git a/src/view/phui/calendar/PHUICalendarMonthView.php b/src/view/phui/calendar/PHUICalendarMonthView.php
--- a/src/view/phui/calendar/PHUICalendarMonthView.php
+++ b/src/view/phui/calendar/PHUICalendarMonthView.php
@@ -294,16 +294,36 @@
       'tr',
       array('class' => 'phui-calendar-day-of-week-header'),
       array(
-        phutil_tag('th', array(), pht('Sun')),
-        phutil_tag('th', array(), pht('Mon')),
-        phutil_tag('th', array(), pht('Tue')),
-        phutil_tag('th', array(), pht('Wed')),
-        phutil_tag('th', array(), pht('Thu')),
-        phutil_tag('th', array(), pht('Fri')),
-        phutil_tag('th', array(), pht('Sat')),
+        $this->getDayHeader(pht('Sun'), pht('Sunday')),
+        $this->getDayHeader(pht('Mon'), pht('Monday')),
+        $this->getDayHeader(pht('Tue'), pht('Tuesday')),
+        $this->getDayHeader(pht('Wed'), pht('Wednesday')),
+        $this->getDayHeader(pht('Thu'), pht('Thursday')),
+        $this->getDayHeader(pht('Fri'), pht('Friday')),
+        $this->getDayHeader(pht('Sat'), pht('Saturday')),
       ));
   }
 
+  private function getDayHeader($short, $long) {
+    $day = array();
+    $day[] = phutil_tag(
+      'span',
+      array(
+        'class' => 'long-weekday-name',
+      ),
+      $long);
+    $day[] = phutil_tag(
+      'span',
+      array(
+        'class' => 'short-weekday-name',
+      ),
+      $short);
+    return phutil_tag(
+      'th',
+      array(),
+      $day);
+  }
+
   private function renderCalendarHeader(DateTime $date) {
     $button_bar = null;
 
diff --git a/webroot/rsrc/css/phui/calendar/phui-calendar-month.css b/webroot/rsrc/css/phui/calendar/phui-calendar-month.css
--- a/webroot/rsrc/css/phui/calendar/phui-calendar-month.css
+++ b/webroot/rsrc/css/phui/calendar/phui-calendar-month.css
@@ -10,12 +10,28 @@
 
 tr.phui-calendar-day-of-week-header th {
   text-align: center;
-  font-size: 11px;
+  font-size: 13px;
   padding: 3px;
   color: {$lightbluetext};
   background: {$lightgreybackground};
 }
 
+tr.phui-calendar-day-of-week-header th .long-weekday-name {
+  display: block;
+}
+
+.device tr.phui-calendar-day-of-week-header th .long-weekday-name {
+  display: none;
+}
+
+tr.phui-calendar-day-of-week-header th .short-weekday-name {
+  display: none;
+}
+
+.device tr.phui-calendar-day-of-week-header th .short-weekday-name {
+  display: block;
+}
+
 table.phui-calendar-view td {
   border: solid #dfdfdf;
   border-width: 1px 1px 0 1px;